Ferrq-concrete flooring member



Sept. 24, 1929. M. M. E. LANcRENoN I FERRO CONCRETE FLOORING MEMBER Filed Jan. 6.*1927 Patented Sept. 24, 1929 UNITED STATES `:MARCEL MARIE EUGNE LANCRENON, OF PARIS, FRANCE FERRO-CONCRETE FLOORING MEMBER Application led January 6, 1927, Serial No. 159,419, and in France January 20, 1926.

Due to the continual search for economy in the construction of flooring members in ferro-concrete, manufacturers have been led to adopt the method which consists in eliminating all stays and forms, and in utilizing pieces which are preliminarily moulded and which are placed in position after the setting of the concrete.

In certain of the devices employed, the beams alone are moulded in Vadvance and the intermediate or flat parts are made up on the spot by the use of forms or hollow pieces disposed between the beams. In this method. the beam is provided with flat part which is Subject to compression stress, only after it has been manufactured, and the connection between the two concrete parts which have been made at different periods may not always prove reliable. It should be further noted that in practice, even for ordinary spans, the beam is subject to sinking to such an extent that it may require a middle support between the end supports.

In other methods, on the contrary, the entire beam is prepared in advance together with the iiat part which is subject to compression stress, thus affording various cross sections resembling those of structural steel beams. Such pieces are placed together so as to form the flooring. But in spite of all efforts to connect the pieces properly, they still remain distinct from one another. A

beam which is loaded will thus bend slightly before it bears upon the adjacent beams, and so on throughout the series, and this defect is all the more serious from the fact that the moulded beams are made narrow to facilitate the handling, and each beam is designed to support only a small part of the load, so that the construction thus loses the principal advantage of concrete which is made up on the spot in a continuous manner and in which the stresses will be distributed to the outlying parts, even to quite a distance.

My invention relates to the construction of flooring which consists of juxtaposed elements or beams in which the aforesaid defects are eliminated by reason of a preliminary elastic deformation of the material and to their state of initial tension or com- `fac-e for the upper story, whilst the bottom fiange forms the ceiling ofthe lower story. An embodiment of my said invention is shown by way of example in the appended drawings.

Fig. 1 is a perspective view of a portion of flooring which consists of beams accordj ing to the invention. Figs. 2, 3 and 4 show a mould for manufacturing the said beams;

Figs. 2 and 3 show the said mould in cross section and elevation, in the respective positions for moulding and removal, and Fig 4 one of the plates limiting the length of the beam.

' The beams l which form the flooring have in each case a C-shape, in which the two horizontal flanges 2 and Sare terminated by the respective ramps V2 and 3, which are situated opposite one another. The vertical web is connected with the said flanges by the inclined planes or bevelled corners 4, 5 so that when the said beams yare placed together, as shown in Fig. l, the ramps 2', 3 of one beam will coincide exactly with the bevellcd parts 4, 5 of the adjacent beam.

Suitable recesses 6 are formed in the said web at stated intervals, having an adequate shape, whereby the beam will be made lighter. forcing bars which are designed according `to customary practice; the reinforcing elements comprise the C-shaped transverse elements which act chiefly against shearing stresses. These secondary members may be advantageouslyinclinedy at 45 degrees with referencefto the axis of the beam.

Since the said beams are placed very close together, the,` ramps 2-3 of each beam will bearagainst the bevelled parts 4-45 of the In addition to the longitudinal rein- L adjacent beam, thus forcing the flanges apart in an elastic manner and producing a tension which is exercised before the structure receives any load, so that the several parts will be connected together in the most approved manner. By reason of the present form of construction, no part of the iiooring will be overhung, since in each case the upper flange is caused to bear so to Speak in the direction of the axis of the adjacent beam. In this manner I am enabled to reduce the thickness to the minimum which is compatible with the proper manufacture.

The said beams can be moulded in a simple and rapid manner by the use of a set of .moulds whose essential features are shown .n Figs. 2,l 3 and 4. The moulding device consists of two parts comprising an inner' and an outer part.

The outer part consists of two U iron members 8 8 with the webs placed in the vertical position and the flanges turned toward the exterior. Between the said members is disposed at the lower part a third U iron member 9 with the web in the h0ri zontal position and the anges extending upwardly. `The member 9 is held in contact' with the members 8 and 8 by suitable clamping means, not shown.

The inner part of the mould consists of two angle pieces 10 and 10 in which the flanges are of unequal length and the angle is rounded; said pieces are pivoted together at 11, and each carries at the end of the long flange an iron member 12-12^of triangular cross section. Upon this inner part are disposed the bosses 13 which are suitably spaced apart and are maintained Eby the pins 14 and serve to form the recesses 6 in .the web of the concrete beam, and they also serve to .adjust :the thickness of t'he web, las Wiill be further specified.

Thelength of the concrete beam is limited vby the members 15 having the form represented in Fig. 4 and comprising the apertures 16 through which may extend the steel reinforcing bars formaking connection with the other elements of the building. Y

The operation is as follows.: A The internal core is .put in place as show in Fig. 2, with the triangular members 12- 12 resting upon the flanges of the lower member 9. The conci'ete is placed between the .members 8-8 and the internal core 10-10, and it is levelled off flush with the bosses 1,3 by means of a tool which forms at the saine time .the YbevelledV parts 4 5. Vhen the concrete Abegins `to set, the bosses 13 vare removed through the apertures 6; Ithe Aclamps holding `together the members 8-`-'8 and the member 9 are removed, and

the said core is xlowered by bringing together its .branches 19-10 3) and it isthen drawn out .inthe ylengthwise direction. The

' settingV of the lbeam can now be completed,

jecting from the top and bottom of the inner side of the vertical portion, the free ends of hese horizontal portions being cut cantwise in a manner corresponding substantially to the cants on the vertical portion, and C- shaped reinforcing bars the en d parts of which are disposed in the horizontal portions perpencliculaily to the vertical portion and the middle part of which is disposed in the verticalportion at an angle of C with the horizontal.

2. A hollow concrete flooring including,` a plurality of parallel similarly disposed C- sliaped beams each -consisting of a vertical portion and two horizontal extensions, oppositely inclined slopes at the outer corners of the vertical portion of each beam, oppositely inclined slopes at the inner corners of the extensions and disposed 'substantially parallel to the corresponding slopes of the vertical portions of the adj acentrbeamsV and adapted to freely slide to allow the vertical portion of one beam to be wedged inside the channel of the adjacent beam and to open the extensions thereof, whereby t'lie beams are mechanically connected more closely as the pressure between the beams is increased,

3. A hollow concrete flooring including a plurality of parallel beams disposed side by side, corners bevelled in opposed direction at the upper and lower ends of the sides of each beam adjacent another Vbeam and facing a 1 given direction, oppositely inclined `slopes formed at the upper and facing the other direction, the cooperating bevelled corners and slopes having corresponding inclinations and being adapted to produce incident to their free sliding movement an elastic wedging of one of the beamswhereby 'the latter are mechanically connected more closely as the beams are pressed together.

In testimony whereof I have affixed my 'l signature.

MARCEL MARIE EUGNE .LANCRENON.

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